It is plain that the range of the above conditions is far beyond anything we have in our globe, and that we are not warranted, from analogy, to come to the conclusion that the bodies of the solar system are, as a whole, inhabited. But, surely, there is no necessity, in order to hold a plurality of worlds, to maintain that inhabitants must be found even in bodies exhibiting extreme conditions. Those who take the broad general ground that matter implies life, must, in order to be consistent, hold that every comet, asteroid, and meteorolite must have its inhabitants; but this position is quite antagonistic to the analogical argument. Analogy would lead us to expect that parts of the solar system would be unfitted for the phenomena of life, though it was admitted that parts were habitable. Our globe may be taken as the type of the whole solar system. Portions of its surface represent the extreme conditions of the planets. The summits of its loftiest mountains and the polar regions may represent Neptune and the other planets on the extreme range of the solar system; the burning sands of the Sahara may represent Mercury and Vulcan, in the immediate neighbourhood of the sun; and just as we find that these extreme portions of the earth's surface are incapable of sustaining inhabitants, so may we legitimately conclude that the extreme portions of the solar system may also be destitute of life. There are desolate parts of the earth's surface of a much larger extent than the whole surface of many
